Remote Inhibit/Remote Reset Controls; Module Current Monitor; Remote Inhibit Control Operation - KEPCO HSM 3.3-230 Operator's Manual

3.12

REMOTE INHIBIT/REMOTE RESET CONTROLS

HSM power supplies incorporate two TTL-level inputs, RC1 and RC2, accessed via the I/O con-
nector, which can be used to disable the output regulator via external stimulus. These two con-
trols operate from an internal 5V supply (5VAUX) which is isolated from both input and output
(see PAR. 3.11), creating a "floating" inhibit control circuit which allows the user to control sev-
eral HSM power supplies operating at different return potentials from a single source. The two
control lines differ in that RC1 (pin 8) is normally high, initiating an output inhibit with application
of a low signal level, while RC2 (pin 7) is normally low and requires application of a high level
signal to inhibit the output; both of these signals are applied with respect to AUXRTN (see Fig-
ure 3-5), and can be operated at potentials as much as ±500V from the HSM output(s).
These two signal levels are TTL-compatible, both for voltage levels and source/sink capability.
If not actively driven, these signals have no effect on power supply operation. Activation of
either one of these control lines results in an immediate shutdown of the output PWM regulator,
including reset of the soft-start, undervoltage, and current walk-in circuits. Operation is inhibited
until the appropriate control line is released, whereupon the power supply output restarts as
from initial cold turn-on.
An additional function which can be derived from the remote inhibit control circuitry is the ability
to reset the overvoltage/undervoltage latch circuitry without cycling the source power (Remote
Lockout Reset). When this function is enabled via switch S1-1, the latch can be reset by tog-
gling one of the inhibit control signals from enable to disable and back. The main advantages of
this remote reset function are the ability to reset the power supply from a remote location and an
instantaneous reset time (compared to the 30-second minimum waiting period imposed when
cycling the source power for reset).
3.13

MODULE CURRENT MONITOR

HSM power supplies provide a 0-5.5V analog signal named IMON, accessed via I/O connector
pin 32, which duplicates the signal level of the load sharing feedback signal (ISHARE) gener-
ated by each HSM. This permits the user to determine the load being provided by each module
within a parallel or redundant power system configuration. The IMON signal is current-limited
HSMSERIES OPR 052912
FIGURE 3-5.

REMOTE INHIBIT CONTROL OPERATION

3-7